In the first dozen slides of the talk I look at the first question "Black heresy: what is therapeutic drift and does it really matter?". Here's a link to the twelve slides (and here's a link to the whole sixty nine slide talk). Basically I argue that, if therapist drift is "an important factor in why ... therapies are commonly less effective than they should be" (Waller & Turner) then high therapist adherence and high therapist competence in particular therapy models should be strongly linked to better outcomes. Presumably too, if therapist drift is a common cause of decreased effectiveness, we would expect therapists as a whole to tend to "drift" more and decrease in effectiveness more the longer they have been in practice.

Well currently the key article on links between adherence, competence & outcome seems to be Webb et al's 2010 paper and the results of their meta-analysis are very clear:

What about experience/outcome links? Well a sit up and blink study here is Choudhry et al's 2005 paper "Systematic review: the relationship between clinical experience and quality of health care" with its abstract reporting "Overall, 32 of the 62 (52%) evaluations reported decreasing performance with increasing years in practice for all outcomes assessed; 13 (21%) reported decreasing performance with increasing experience for some outcomes but no association for others; 2 (3%) reported that performance initially increased with increasing experience, peaked, and then decreased (concave relationship); 13 (21%) reported no association; 1 (2%) reported increasing performance with increasing years in practice for some outcomes but no association for others; and 1 (2%) reported increasing performance with increasing years in practice for all outcomes." Wow ... BUT this is a study on physicians. So choose your medical practitioner with care, maybe be cautious about older doctors.

What about psychotherapists? Is there are a similar pattern of deteriorating effectiveness with age ... possibly due to "therapist drift" or "therapist failure to update"? Well no ... there isn't:

Waller & Turner's claim that "Therapist drift ... is an important factor in why ... therapies are commonly less effective than they should be in routine clinical practice." I don't think that current research evidence supports this statement. It seems to me less "black heresy" and more "red herring". However, as the slide above highlights, we do face major problems as psychotherapists when we consider, for example, Okiishi et al's finding that "client recovery could not be shown to be a function of differences in therapist ... professional training, professional experience, or theoretical orientation". Now this looks like a really significant problem. For more about these major challenges to our field, see the next blog post in this sequence - "Psychotherapy is helpful but has developed shockingly poorly over the last thirty years".

This has implications of medieval back-sliding or heresy: we train in a particular 'method' or 'modality'. Hopefully this is reasonably 'evidence-based' and effective (the two are not the same). Most psychotherapists - and not just the one's I know - 'extend' their way of working over their professional career - a raison d'être for a good choice of CPD topics. This is not "drifting" away from their original method, this is healthy growth and development - and we should welcome it.
Maybe one of the reasons why psychotherapy has not developed as fast as it should over the last 120 years is because of this 'insistence' on a form of purism, or in the rigidity of the 'methodologies'.
There are - of course - obvious dangers as well: adding in a new (say esoteric or body-oriented) technique doesn't make you into a transpersonal psychotherapist or a somatic psychotherapist: there is a lot more to it than that and we can suddenly become dabbling amateurs, out of our depth, when dealing with a different client group, or set of 'difficulties' that we are not fully prepared for, cognisant about, or trained in.